Nonhardening vacuum tube lamp



Oct 6,1931. 1.. L. BECK 1,826,385

NONHARDENING VACUUM TUBE LAMP Filed June 2 192 gvwentoz LEO L. BEC K?atented @ct. 193i sates LEO L. BECK, OF LINDEN, NEW JERSEY, ASSIGNOR TOCLAUDE NEON LIGHTS, INC., OF

NEW YORK, N. Y., A CORPORATION OF NEW YORK NONHABDENING VACUUM TUBE LAMPApplication filed June 2, 1926. Serial No. 113,147.

This invention relates to vacuum tube lights, and more particularly tolights in which a column of gas under low pressure, such as neon, iscaused to glow by the passage of an electric current therethrough.

Lights of this type, as is well known, have a life that is limited, asat present constructed. After they have been in operation for a certainlength of time, the voltage required to operate them increases to suchan extent that the light is for all practical purposes inoperative. Thisprocess is termed in the art hardening and is known to be due to alowering of the pressure of the gas within the tube.

While it might be supposed that this hardening is due to leakage of gasfrom the tube, it has been found that this is not the case. At least,the phenomenon is mainly due to causes other than leakage of gas fromthe tube.

It is an object of the invention to provide a method and apparatus forpreventing, or at least materially delaying the hardening of vacuum tubelights such as neon lamps.

It is a further object of my invention to provide a vacuum tube lighthaving an operating life greatly in excess of the operating life ofknown tubes of the class described.

It is a further object of this invention to provide a vacuum tube lighthaving means introduced therein to prevent or materially delay thehardening of such lights in operation.

Still other objects of my invention will be apparent from thespecification.

The features of novelty which I believe to be characteristic of myinvention are set forth with particularity in the appended claims. Myinvention itself, however, both as touts underlying principles and as toits practlcal application, will best be understood by reference to thespecification and accompanying drawings, in which Figure 1 represents avacuum tube light in accordance with my invention; and Figures 2, 3, 4,5 and 6 represent a method of introducing unheated glass chips which Iprefer to use in practising my invention.

It has been found that this lowering of the gas pressure or' hardenin isnot due to leakage of gas from the tufie but isdue to a totallydifferent cause. It is generally believed that when a voltage isimpressed between the electrodes of a vacuum tube light, such as a neonlamp of the type shown, electrons pass into the gas and travel towardthe other electrode. During their passage, they cause the neon to glowand radiate its characteristic light. Some of these electrons. however,in passing from the electrodes to the gas, appear to carry off tinyparticles of metal from the electrode, which particles are plljated outor deposited on the walls of the tu e.

It has been found that these metal particles, of perhaps atomic order ofsize, in their passage through the gaseous space of the tube, pick up orentrap molecules or particles of neon, and carry these gas particleswith them. When the metal particles are plated out on the wall of thetube, the neon which they have entrapped no longer plays any art in theoperation of the tube and eventua ly so much neon is entrapped andeffectively removed that the gas pressure falls below that desired andthe voltage required to cause illumination increases greatly. When thistakes place, the practical operating life of the tube is at an en It isknown that when an electric current is passed through a mixture of gasesfrom metallic electrodes, the metal particles passing through thegaseous space entrap and carry off first the lightest gas of themixture. and leave the heavier gases until the lighter are removed. Forexample, if hydrogen is admitted to a neon light, even in quantitiessmall enough so that the operating characteristics of the tube areotherwise not affected, the metal particles will entrap and carry offthe hydrogen as long as it is present, and the neon will be left.

I have found that this effect may be utilized to increase the length ofuseful operating 9 life of vacuum tube lights such as neon lamps, byarranging or providing for a slow evolution or introduction of hydrogen,or other substance having a similar effect, in the tube.

The result of this is that there will always 1 The Ttube 11 will besealed to be hydrogen present in the tube and so long as it is presentthe neon or other active constituents will not be removed. Duringoperation of the tube the hydrogen will be plated out, and bycontrolling the rate of evolution or introduction of the hydrogen in thetube in such a way thatit'is produced approximately as fast as it isremoved, a balanced operating condition ,is achieved which results in atubehaving an operating life greatly in excess of ordinarytubes.

The slow introduction or evolution of hydrogen necessary may be providedfor in several ways, but I prefer to obtain it by introducing into thelamp envelope after exhaustion, some ordinary unheated glass, preferablyin the form of chips, which may be distributed along the path ofdischarge between the electrodes of the lamp.

Referring now to the figure, 1 designates a tubular envelope oftransparent material such as glass, having electrodes 2 disposed withinthe tubes, and supported on strings of glass beads 3 strung on wire, andconnected to lead-in Wires 4 passing through a press 5. The space in thetube 1 is occupied by gas such as neon at relatively low pressure.

Unheated ordinary glass chips 6 are introduced into the. tube in anysuitable way, but preferably in the way described and claimed in thecopending application of Robert Smalley, entitled Method and apparatusfor introducing foreign substances into vacuum tube lamps, etc. filedApril 30, 1926, assigned to Claude Neon Lights, Inc. By unheated glasschips, I mean small particles or chi s which are substantially unheatedduring t e exhausting process.

Referring now to Figure 2, 11 designates a section of tubing preferablyof glass having a second portion 12 sealed thereon to form a T. Thelower end of the stem of the T is closed off as at 13 and the substanceto be transferred to the interior of the lamp such as the unheated glasschips, is placed therein as indicated at 14. If desired, a neck portion15 may be formed on the T on each side of the stem thereof, or at oneside only if desired for convenience in sealing off and removingportions of the tube.

Referring now to Figure 3 I have shown diagrammatically a lamp envelope1 in which it is desired to insert unheated glass chips 6.

the lamp envelope 1 as at 22 in such a manner as to establish contactbetween the interior of the T tube and the interior of the lampenvelope. The junction 22 between the T tube 11 and the lamp envelope 1should be made air tight for a purpose which will be explained later.The opposite open end of the T tube 11 ma and preferably will beconnected to tube 23 leading off to suitable pumps or other evacuatingapparatus, not shown so that the lamp may be evacuated through tube 11,thereby 5 burner 25 to the any necessary heating of the lamp envelopemay take place at'this time either with or without the passage ofcurrentthrough the lamp and either with or without supplemental heating of theelectrodes to drive off occluded gases.

Since the material to be introduced is in the pocket 14 out of the pathof current flow in the gas, the passage of current will not materiallyheat the substance to be intro duced into the lamp and thereby drive offthe water vapor which it contains, this of course must be avoided.

After the tube has been properly evacuated, the evacuating apparatus maybe dis- 1 connected, and the proper amount of desired gas, such forexample as neon, introduced by opening a valve (not shown) in theevacuating line.

It is now evident that the tube has been evacuated and that it has beensupplied with the proper amount of gas for operation. It should now besealed 011' which may be done, for example by bringing a flame from aburner 25 to play upon the tube 11 between the junction of the T and theconnection to the exhaust line.

The tube may now be aged and tested to make sure that it has the properoperating characteristics, before the introduction of the foreignsubstance. After the tube has been tested and found in good order thelamp envelope with the T tube attached thereto may be manipulated in asuitable manner to cause the foreign substance such as the glass chips 6to flow down the stem of the T and down the top thereof as shown inFigure 5,. into the envelope 1 of the lamp proper. The simplest way ofproducing this result is simply to invert and tilt the lamp after whichthe T tube may be tapped gently to dislodge the glass chips.

The substance has now been introduced and the lamp will now have thedesired operating characteristics. However, the T tube, or what remainsof it protrudes from the envelope and might be accidentally fracturedthereby ruining the lamp. Therefore I prefer to seal off and remove whatis left of the T tube as shown in Figure 6 by bringing the junctionpoint 22 of the T tube and the lamp and sealing off and removin the Ttube as will be readily understood.

hile I do not wish to be bound by any explanation of the effect of theunheated glass chips, I believe that a slow and long continued evolutionof water vapor takes place from the chips in the path of the dischargebetween the electrodes, and that this water vapor disassociates intohydrogen and oxygen. The hydrogen thus liberated is entrapped andremoved by the metal particles, leaving the neon in its gaseous freestate, and the rate of evolution of hydrogen is such that it is producedat about the same rate as it is removed. The quantity produced isdependent upon the quantity of glass chips introduced. Of course, it isto be understood that the chips must not be subjected to heating duringthe exhausting of the tube since that would remove the water vapor whichthey carry, nor is it necessary to wet them, as they carry suflicientwater for the purpose even when they would ordinarily be considered dry.

I have found that unheated platinum produces the same effect, but is notso desirable because of its cost and because, being a conductor, ittends to short-circuit the discharge through the gas.

\Vhile I have described my invention and given what I believe to be theproper explanatigm for the actions which take place in the tu e, I amnot limited thereby. I do know that the introduction of suitable foreignsubstances, such as unheated glass, unheated platinum, etc., has amarked effect in increasing the life of a vacuum tube li ht, such as aneon lamp, whatever the theoretical explanation may be, and I do notwish to be limited to any theory of action.

While I have shown and described certain preferred forms of myinvention, it is clear that modifications and changes may be madewithout departing from the spirit and scope of my invention, as will beevident to those skilled in the art.

What I claim is:

1. A method of increasing the lift of neon positive column tube lampscomprisin a column of gas containing neon, energize by an electriccurrent, which comprises sealing in contact with the gas in the lamenvelope 8. foreign substance which will malntain a slow evolution ofwater vapor into the interior space of said lam 2. A method 0 increasingthe lift of neon positive column tube lamps comprising a col umn of gascontaining neon, energized by an electric current, whichcomprisessealing in contact with the gas in the lamp envelope a quantity of lasscarrying water therewith.

3. A meth of increasing the life ofmeon positive column tube lampscomprisin a column of gas containing neon, energize by an electriccurrent, which comprises scaling in contact with the gas in the lampenvelope a quantity of unheated glass. 7

4. A method of increasing the life of posi- I wish it distinctlyunderstood that tive column tube lamps comp-rising a column of gas atrelatively low pressure energized by electric current which comprisesmaintaining within the lamp envelope a relatively slow evolution ofwater vapor.

5. A method of increasing the life of positive column tube lampscomprising a column of gas comprising neon at relatively low pressureenergized by electric current which comprises maintaining within thelamp envelope a relatively slow evolution of water vaor. p 6. A positivecolumn tube lamp comprising a column of gas at relatively low pressure,adapted to be energized by an electric current and containing within thelamp env'elope a substance capable of maintaining a slow evolution ofwater Vapor within the envelope.

7. A vacuum tube lamp comprising a column of gas at relatively lowpressure, adapted to be energized by an electric current and containingwlthin the lamp envelope a quantity of unheated glass capableofliberating water vapor at a relatively slow rate in said envelope.

8. A positive column tube lamp comprising a column of gas comprisingneon at rela tively low pressure, adapted to be energized by an electriccurrent and containing within the lamp envelope in the path of dischargea quantity of unheated glass.

In testlmony whereof I have hereunto set my hand this 21 day of 21%:1926 L O L. BECK.

